"use strict";
// 字符串 可以用 '' "" `` 定义
let username = "李兵";
//数值
let myage = 18;
myage = 18.13;
myage = -18;
// 布尔值 true false
let hasMoney = false;
hasMoney = true;
// undefined null
let unde = undefined;
let nul = null;
